Controller for pneumatically-operated hoists



CONTROLLER FOR PNEUMATICALLY-OPERATED noxsws Filed July 11, 1966 E. R. POWELL July 29, 1969 2 $heetsSheet 1 /76 U v4 Z2 s T 1Z 6 a 02 W N 2 7 M W R m m 05 Q Em a; 0 a- E 4 m a 4 w 2 7 l J z r 7 w/ AM u.

July 29, 1969 E. R. POWELL 3,457,837

CONTROLLER FOR PNEUMATICALLY-OPERATED HOISTS Filed July 11, 1966 2 Sheets-Sheet 2 j 5-- V4 V4? CEMM QMM United States Patent 3,457,837 CONTROLLER FOR PNEUlSt IATICALLY-OPERATED H01 TS Edgar R. Powell, Birmingham, Mich, assignor to D. W.

Zimmerman Mfg. Inc., Madison Heights, Mich, a corporation of Ohio Filed July 11, 1966, Ser. No. 564,295 Int. Cl. F151) 11/16; B66c 1/08; (105d 11/00 U.S. Cl. 91-447 7 Claims ABSTRACT OF THE DISCLOSURE An air controller for an air-operated hoist is provided. The air-operated hoist is of the type in which air pressure acts on a piston which moves a hoist drum mounted on a ball screw. The controller has all components integrated into one body mounted on the hoist housing with the controller being less expensive to manufacture and assemble and being capable of being readily replaced on the hoist housing in the event of a defect or failure of the controller.

This invention relates to a controller for a pneumatic hoist used to facilitate the handling of loads.

A pneumatic hoist embodying the invention includes a chamber or cylinder to which a fluid, usually air, is supplied under pressure. The air pressure acts on a piston which, in turn, moves with a hoist drum mounted on a ball screw and arranged so that the piston moves toward the chamber as the load is lowered and moves away from the chamber as the load is raised. With the air under appropriate pressure, most of the load carried by the hoist is offset or balanced by the air pressure so that a small force on behalf of the operator is required to raise or lower the load, with this force usually being up to about ten percent of the actual weight of the load. The hoist operator can thereby manipulate the load, including raising and lowering it, as though it weighed but a few pounds. The operator thus exercises and uses the same muscles he otherwise would if carrying a load directly, but without the concomitant strain and exertion. In addition, even an inexperienced operator has complete control over the load and can move it about rapidly, in contrast with the skill and time required to operate an electric hoist, for example, with facility. With the pneumatically-operated hoist, even an inexperienced operator can manipulate a load more rapidly than a highly skilled operator using a conventional electric hoist or the like.

The basic hoist unit, when used with different controls, can be employed for other purposes. For example, the basic hoist can be used to actually raise and lower loads with the aid of air pressure and without any handling of the load by the operator at all. In this manner, the hoist operates more like a conventional hoist, but has the additional advantages that the load can be physically raised or lowered a few inches from a given position by the operator, simply by grasping the load, if desired. A hoist of this type is shown in my co-pending application, Ser. No. 516,620, now Patent No. 3,325,148. With still other controls, the basic hoist structure can be used as a tool balnacer, as discussed and shown in my co-pending application, Ser. No. 518,287.

The present invention relates to a controller for a basic hoist unit capable of operating the unit as a pneumatically-operated balancing hoist, a first described above. The new controller is arranged so that all components thereof are integrated into one housing or body which can be mounted on the housing of the hoist unit and removed therefrom in a very short time. Other suitable controls can then be quickly substituted to enable Patented July 29, 1969 the hoist unit to be operated as a more conventional hoist or as a tool balancer, by way of example, as discussed above. Also, the controller can be readily mounted on different basic hoist units of different sizes to handle loads of a wide variety of sizes.

The new controller, by integrating the various individual controls into one body, is less expensive to manufacture than the combined individual controls heretofore employed, and the assembly costs of the various controls, piping, and fittings also is substantially eliminated. Further, if a problem in the controls develops while the hoist is in operation, another controller can be substituted for the defective one so that the down time of the hoist can be a matter of a few minutes. The defective controller can be removed to a remote location and repaired at leisure.

The controller according to the invention also includes a unique air pressure control which is capable of regulating air pressure more closely than heretofore, and has an improved means for venting air from the system.

It is, therefore, a principal object of the invention to provide a pneumatically-operated hoist having a controller containing all control components in a single body.

Still another object of the invention is to provide a controller with an improved air pressure regulator capable of closely controlling and venting air pressure for the hoist.

Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment thereof, reference being made to the accompanying drawing, in which:

FIG. 1 is a view in perspective of a pneumatically-operated hoist shown mounted on a rail and carrying a load;

FIG. 2 is a view in vertical, longitudinal cross section of the hoist shown in FIG. 1;

FIG. 3 is a somewhat schematic view in cross section of a controller embodying the invention and used with the hoist unit of FIGS. 1 and 2;

FIG. 4 is a view in elevation of the actual controller of the invention; and FIG. 5 is a view in cross section taken along the line 5- 5 of FIG. 4.

Referring to the drawings, and more particularly to FIG. 1, a pneumatically-operated hoist embodying the invention is indicated at and is suspended from a con veyor rail 12 by a trolley 14. A load 16 is suspended from the hoist by a suitable hoist hook 18 and a hoist cable 20. Raising and lowering of the load 16 is easily accomplished by hand since most of the weight of the load is counterbalanced by air pressure. This pressure is controlled by a vent or exhaust line 22 and a manually-operated control Valve 24.

Referring to FIG. 2, the hoist 10, as shown in longitudinal cross section, includes a housing 26 having end walls 28 and 30. A ball screw 32 extends longitudinally through the housing 26 and is fastened at each end centrally to the end walls 28 and 30. A ball screw assembly 34 is mounted on the ball screw 32 and moves longitudinally in the housing 26 when turned relative to the ball screw. A cable drum 36 is mounted on the ball screw assembly 34 and moves therewith both rotatably and longitudinally relative to the screw 32. The drum 36 has a shallow helical groove 38 therein which receives the hoist cable when the load is raised and the cable is wound on the drum. One end of the cable 20 is suitably afiixed to the drum at one end of the helical groove.

A thrust bearing 40 located adjacent the drum 36 bears against a hub portion 42 of the drum. The bearing 40 is engaged by a piston 44 which has a peripheral seal 46 contacting the housing 26 in gas-tight relationship. The second end wall 30, the right hand portion of the housing 26, and the piston 44 form a power chamber 48 to receive air or other suitable fluid for operating the hoist. An ring seal 50 located in the piston 44 enables the piston to be supported in slidable but sealing contact with a sleeve 52 mounted over the right end of the ball screw 32.

When air is supplied to the power chamber 48 and is under sufiicient pressure, the piston 44 moves toward the left, as shown in FIG. 2, and, through the thrust bearing 40, causes the drum 36 and the ball screw nut assembly 34 to move in the same direction. During this movement, the ball screw nut assembly 34 rotates the drum 36 in a manner to raise the cable 20 and the load 16. When the load exceeds the air pressure, the piston 44- is moved to the right and forces air out of the power chamber 48.

Air is supplied to and exhausted from the chamber through an opening 54 from a controller 56 embodying the invention. The controller 56 comprises a housing or controller body 58 having integral mounting flanges 60 and 62 (FIG. 4). The body 58 is attached to the end wall 30 by four bolts 64 extending through the flanges. With this arrangement, the entire controller can be quickly attached to and removed from the end wall by means of the four bolts.

As shown somewhat schematically in FIG. 3, the controller body 58 is threaded to receive an air supply fitting 66 to enable air to be supplied from a line 68 to a supply chamber 70 containing a filter 72. From here, the main air is supplied through a main air regulator 74, past an airoperated check valve 76, and through an inlet passage 77 to the chamber 48. Air from the supply chamber 70 also passes throuhg a pilot air regulator 78, through a trim valve 80, an auxiliary valve 82, and through the vent line 22 to the manually-operated control valve 24. The pressure of the air from the pilot air regulator 78 controls the main air pressure from the main air regulator 74 with the pilot air pressure being changed as desired by the handoperated valve 24.

The hand-operated control valve 24 is of a three-position type as discussed more fully in my copending application, Ser. No. 315,873, now Patent No. 3,260,508. In one position of the control valve 24, as shown in FIG. 3, the pilot air is not vented at all but is completely blocked so that the maximum pressure of pilot air as determined by the pilot air regulator 78 is applied to the main air regulator 74 and the highest pressure air is supplied to the power chamber 48 of the hoist unit. With this setting, the hoist can handle the heaviest weight to be manipulated with the aid of the hoist. The control valve also has a second position in which the line 22 is aligned with a vent opening 84 controlled by a needle valve 86. The valve 86 is set so that a small amount of air Will be bled through the line 22 so that the pilot air pressure will accordingly be decreased and the main air pressure will also be decreased. The valve 86 is set so that the pressure will enable the hoist to handle a load of intermediate weight in a manner similar to the heaviest weight. The vent line 22 also can be aligned with a second vent opening 88 controlled by a second needle valve 90. This needle valve is set so that maximum pilot air will be exhausted through the line 22 to enable the main air pressure to be at a minimum whereby the hoist hook 18 can be manipulated up and down as if it were substantially weightless.

Referring in more detail to the components of the controller 56, the pilot air regulator 78 is connected with the supply chamber 72 through a short pilot air passage 92 communicating with an opening 94. The opening 94 has a valve stem 96 extending therethrough which carries a valve 98 for controlling the opening 94. The valve 98 is urged toward the opening by a suitable coiled spring 100 located therebelow. In a pilot air chamber 102 above the opening 94 is a transversely extending diaphragm 104 having a bleed passage 106 centrally located therein and aligned with the upper end of the valve stem 96. A pressure spring 108 urges the diaphragm 104 downwardly with the pressure of the spring 108 regulated by an adjusting screw 110. The screw 110 changes the pressure of the spring 108 on the diaphragm 104 and thereby changes the pilot air pressure. The vent passage 106 through the diaphragm 104 serves to release pressure in the chamber 102 in the event that the screw 110 is tightened excessively and is then unscrewed, with the air at the excessively high pressure otherwise being trapped in the absence of the vent passage 106.

The regulated pilot air is supplied through an inlet passage 112 past the trim valve and into a pilot air chamber or bonnet 114 of the main air regulator 74. The pressure in the chamber 114 determines the pressure of the main air and the trim valve 80 adjusts the rate at which the pilot air flows into the chamber 114 and consequently, the rate of change of the main air. This, in turn, controls the speed at which the hoist responds to changes in the pilot air pressure as determined by the manually-operated valve 24.

From the chamber 114, the pilot air passes through an outlet passage 116 and past the auxiliary valve 82 to the control valve 24. The auxiliary valve 82 can be used to control the venting of the pilot air in place of one of the needle valves 86 or in some applications. By setting the auxiliary valve 82 to be slightly more restricted than the valve 86, the auxiliary valve 82 will control the pilot air flow when the valve 86 is aligned with the flexible exhaust hose 22. By using the auxiliary valve in this manner, in the event that the hose 22 should break, the load carried by the hoist will not drop suddenly but will move down relatively slowly as determined by the rate of flow of pilot air past the valve 82.

Most of the air from the chamber 70 passes through a main air inlet 118 to a valve chamber 120 of the main regulator 74. A main opening 122 connects the valve chamber 120 with a main air regulator chamber 124. A hollow valve stem 126 extends into the opening 122 and carries a valve body 128 having a resilient valve ring 130 cooperating with an annular valve seat 132. The valve body 128 has a small longitudinal passage 134 near the stem 126, which passage enables the pressure in a lower spring chamber 136 formed by a spring-retaining nut 137 to equal that in the main chamber 124. An annular surface 138 of the valve body 128, which surface is subjected to the regulated air, exceeds the area of an upper annular surface 140 which is also subjected to the regulated air. Consequently, the regulated air tends to urge the valve 130 toward the closed position. Outside the annular valve seat 132, a lower surface or shoulder 142, which is subjected to unregulated air, is substantially equal in area to an upper surface 144 so that the effect of the unregulated air is balanced. Even though the regulated air exerts an upward force on the valve body 128, a regulating spring 146 also is used to urge the valve body upwardly toward the closed position. A main regulating diaphragm 148 separates the pilot air chamber 114 and the main regulating chamber 124 with the diaphragm urged downwardly by the pilot air pressure. The diaphragm 148 has a central socket 150 carrying an upper ball 152 of a vent control link 154. The link 154 also has a lower ball 156 constituting a valve for closing oif an upper end of an exhaust passage 158 in the valve stem 126. The design of the link 154 is important to obtain effective air regulation. The upper ball 152 in the socket 150 enables the link to swivel somewhat to accommodate any misalignment between the diaphragm 148 and the exhaust passage 158. Further, the spherical design of the lower valve 156 effectively fits in the upper end of the cylindrical passage 158 in sealing relation even though some misalignment may exist. While the spherical shape is preferred, the valve 156 also can be semi-spherical, conical, or of truncated conical shape, with good results still being obtained. In any event, the shape is such that the valve 156 is circular in cross section taken through a plane perpendicular to the link 154, with the cross section decreasing in diameter in a direction away from the link 154 and toward the stem 126 at least for the extremity of the valve which seats in the exhaust passage 158.

The regulated air from the chamber 124 passes to an outlet passage 160 to the passage 77. From here, the air enters the power chamber 48 and urges the piston and drum toward the opposite end of the hoist. When the load is moved downwardly by the operator, to urge the hoist piston toward the power chamber, the air in the chamber, when exceeding a predetermined pressure, causes the main diaphragm 148 to move upwardly and unseat the valve 156 from the hollow stem 126. The air thereby bleeds through the passage 158 until the operator releases the downward force on the load. Similarly, when the operator raises the load, the piston moves away from the power chamber 48, causing the pressure therein to decrease. The air pressure in the upper chamber 114 then urges the diaphragm 148 downwardly and, through the link 154, causes the valve body 128 to move downwardly away from the seat 132, thereby enabling additional air to enter the power chamber '48 through the main regulator chamber 124.

In the event that the main air supply fails, the load carried by the hoist ordinarily would drop suddenly. To prevent this, the air-operated check valve 76 is used. This includes a valve stem 162 having a valve 164 seating against a shoulder 166 in the passage 160, when the valve is in a right hand position. The valve stem has a piston 168 which is located in a cylinder 170 to which the main air is supplied through a passage 172 communicating with the valve chamber 120. When the supply air is at its normal pressure, the pressure of the air in the chamber 170 urges the piston 168 toward the left against the force of a spring 174 held by a retaining nut 176. When the pressure falls, however, the spring 174 pushes the piston 168 and the valve stem 162 toward the right to cause the valve 164 to seat against the shoulder 166 and thereby enable the air in the power chamber 48 to be trapped, thereby preventing dropping of the load.

As discussed previously, the controller 56 has many advantages over the separate control components heretofore used. The overall controller 56 can be quickly attached to and removed from the cover 30 by means of the four bolts to enable the controller to be replaced by a different control unit or to enable the control unit to be repaired with a substitute controller used in place of the defective one. The controller 56 also is less expensive than individual, separate components and the cost of assembling the various components along with their associated piping and fittings is eliminated. Further, all of the adjustments for the controller 56 are readily available. The pilot air is easily regulated by the screw 110 and for this purpose can be provided with a siutable knob 178 (FIG. 4). The trim valves 80 and 82 also are slotted for adjustment and are readily accessible, as shown in FIG. 4.

What I claim is:

1. In combination, a pneumatically-operated hoist having a hoist housing, said housing forming a power chamber, means subjected to air in said power chamber for aiding in raising and lowering a load, a pressure regulator for controlling the pressure of air to said chamber, said regulator comprising a regulator housing, a diaphragm extending across said regulator housing and partly defining a main air chamber, said diaphragm having a centrally-located socket directed toward said main air chamber, a main inlet in said main air chamber for air to be regulated, a main outlet in said main air chamber for the regulated air, a valve assembly between said main air inlet and said main air chamber comprising a valve stem, a valve body, a valve carried by said valve body, and an annular valve seat, resilient means for urging said valve body and said valve toward said valve seat, said stem having a passage extending therethrough and communicating with the atmosphere, a valve link, a ball on said link received in said socket to connect one end of said valve link to the central portion of said diaphragm to enable said valve link to oscillate with respect to said diaphragm, and a valve member at the other end of said valve link and cooperating with said valve stem to open and close said valve stem passage.

2. In combination, a pneumatically-operated hoist having a hoist housing, said housing forming a power chamber, means subjected to air in said power chamber for aiding in raising and lowering a load, a pilot air-controlled regulator for controlling the pressure of air to said chamber in accordance with the pressure of pilot air supplied to the regulator, said regulator comprising a regulator housing, a diaphragm extending across said regulator housing and separating said regulator housing into a pilot air chamber and a main air chamber, a main inlet in said main air chamber for air to be regulated, a main outlet in said main air chamber for the regulated air, a valve assembly between said main air inlet and said main air chamber comprising a valve stem, a valve body, a valve carried by said body, and an annular valve seat, resilient means for urging said valve body and said valve toward said valve seat, said valve body and said valve presenting approximately equal opposite areas toward unregulated air, said body and said valve presenting a larger area toward the regulated air in a direction to urge said valve toward said valve seat than in the opposite direction, said stem having a passage extending therethrough and communicating with the atmosphere, a valve link having one end movably connected to a central portion of said diaphragm and cooperating with said valve stem at the other end to open and close said valve stem passage.

3. In combination, a pneumatically-operated hoist having a hoist housing, said housing forming a power chamber, means subjected to air in said power chamber for aiding in raising and lowering a load, a pressure regulator for controlling the pressure of air to said chamber, said regulator comprising a regulator housing, a diaphragm extending across said regulator housing and partly defining a main air chamber, said diaphragm having a centrally-located socket directed toward said main air chamber, a main inlet in said main air chamber for air to be regulated, a main outlet in said main air chamber for the regulated air, a valve assembly between said main air inlet and said main air chamber comprising a valve stem, a valve body, a valve carried by said valve body, and an annular valve seat, resilient means for urging said valve body and said valve toward said valve seat, said stern having a passage extending therethrough and communicating with the atmosphere, a valve link, means pivotally connecting one end of said valve link to a central portion of said diaphragm to enable said valve link to pivot in all directions, and a valve member at the other end of said valve link and cooperating with said valve stem to open and close said valve stem passage, said valve member having a circular cross section in a plane substantially perpendicular to said link, with the diameter of the cross section decreasing in a direction away from said link.

4. The combination according to claim 3 characterized by said valve member of said link being substantially spherical.

5. In combination, a pneumatically-operated hoist having a hoist housing, said housing, forming a power chamber, means subjected to air in said power chamber for aiding in raising and lowering a load, a controller for controlling air to said chamber comprising a body, means for mounting said body on said hoist housing, said body having a main air outlet communicating with said chamber, said body having a main air inlet, a pilot air regulator in said body, passage means in said body connecting said main air inlet and said pilot air regulator, a main air regulator in said body having a main diaphragm separating a pilot air chamber and a main air chamber, passage means in said body connecting said pilot air regulator and said pilot air chamber, passage means in said body connecting said main air inlet with said main air chamber, passage means in said body connecting said main air chamber with said main air outlet, said main air chamber having a valve assembly for regulating flow of air from said main air inlet to said main air outlet to maintain the pressure of the air at said main air outlet at a predetermined value, a needle valve in the passage means connecting said pilot air regulator and said pilot air chamber to control flow therethrough, pilot air outlet passage means in said body communicating with said pilot air chamber, and a needle valve in said pilot air outlet passage means communicating with said pilot air chamber to control flow of air therethrough.

6. The combination according to claim 5 characterized by said valve assembly having a vent, and remotely operated vent means communicating with said pilot air outlet passage means.

7. In combination, a pneumatically-operated hoist having a hoist housing, said housing forming a power chamber, means subjected to air in said power chamber for aiding in raising and lowering a load, a controller for controlling air to said chamber comprising a body, means for mounting said body on said hoist housing, said body having a main air outlet communicating with said chamber, said body having a main air inlet, a pilot air regulator in said body, passage means in said body connecting said main air inlet and said pilot air regulator, a main air regulator in said body having a main diaphragm separating a pilot air chamber and a main air chamber, passage means in said body connecting said pilot air regulator and said pilot air chamber, passage means in said body connecting said main air inlet with said main air chamber, passage means in said body connecting said air chamber with said main air outlet, said main air chamber having a valve assembly for regulating flow of air from said main air inlet to said main air outlet to maintain the pressure of the air at said main air outlet at a predetermined value, and an air-operated check valve in said body for preventing fiow of air out of said power chamber through said main air outlet in the event of failure of the air supply to the main air inlet.

References Cited UNITED STATES PATENTS 1,479,386 1/1924 Hynes et al. 91-437 3,286,989 11/1966 Bangerter et al. 254-186 3,313,212 4/1967 Baker et a1. 13785 3,357,443 12/1967 Brumm 137116.5

FOREIGN PATENTS 403,787 1/1934 Great Britain.

PAUL E. MASLOUSKY, Primary Examiner US. Cl. X.R.

M050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 57, 7 Dated July 29, 1969 Inventor-(s) Edgar R Powell T It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

I-. In column 1, line 63, "balnacer" should read --balancer In column 3, line 30, "throuhg" should read through In column 5, line 52, "siutable" should read suitable In column 8, line 5, after "said" (second occurrence) and before "air", insert main SIGNED AND SEALED DEC 2 3 1989 (SEAL) .Aucat:

Edmu-Fkwlm'k WILLIAM E. comm, .m. Attesting Officer Commissioner of Patents 

